Centrifuge and discharge means therefor

ABSTRACT

In a centrifuge comprising a housing, a drum and a clearing knife; the knife carrier having a pivot shaft pivotable mounted in a holding part; the improvement that said holding part is pivotably mounted in said housing; the axis of said shaft and the axis of said holding part are parallel to, and apart from each other; guide means connected to said housing and serving to guide said knife carrier - during turning of said holding part - so as to keep the cutting angle between said knife and the layer to be cleared out at least approximately constant.

llnited States Patent 91 Hausmann [4 1 May 29, 1973 [54] CENTRIFUGE AND DISCHARGE MEANS THEREFOR [75] Inventor: Ernst Hausmann, l-lorgen, Switzerland [73] Assignee: Escher Wyss Limited, Zurich, Switzerland [22] Filed: Dec. 6, 1971 21 Appl. No.: 205,021

[30] Foreign Application Priority Data Dec. 16, 1970 Switzerland ..l8550/70 [52] U.S. Cl ..233/46 [51] Int. Cl. ..B04b l/00 [58] Field of Search ..233/3, 7, 46, 47 R, 233/27, 28

[56] References Cited UNITED STATES PATENTS l/194l Pecker ..233/46 X 774,821 11/1904 Berrigan ..233/7 FOREIGN PATENTS OR APPLICATIONS 1,017,985 10/1954 Germany ..233/6 Primary Examiner-George I-I. Krizmanich Attorney-Austin P. Dodge and Robert A; Ostmann [57] ABSTRACT In a centrifuge comprising a housing, a drum and a clearing knife; the knife carrier having a pivot shaft pivotable mounted in a holding part; the improvement that said holding part is pivotably mounted in said housing; the axis of said shaft and the axis of said holding part are parallel to, and apart from each other; guide means connected to said housing and serving to guide said knife carrier during turning of said holding part so as to keep the cutting angle between said knife and the layer to be cleared out at least approximately constant.

8 Claims, 6 Drawing Figures CENTRIFUGE AND DISCHARGE MEANS THEREFOR BACKGROUND OF THE INVENTION The invention relates to a clearing centrifuge comprising a clearing knife which is arranged inside the drum, is fixed on a knife carrier and is pivotable relatively to a holding part.

For emptying solids which have been centrifuged until dry from the centrifuge drum of a clearing centrifuge, it is known to use a clearing knife in the form of a blade, which knife is connected fast by means of at least one arm to a pivot shaft extending parallel to the drum axis. Since the pivot shaft extending into the interior of the drum usually has to be arranged for constructional reasons close to the drum periphery, the cutting edge of the clearing knife is disposed on a relatively small turning radius, which has the result that the cutting angle during the clearing operation is considerably altered and consequently does not correspond to the best possible cutting conditions over the major parts of the operating range.

SUMMARY OF THE INVENTION The object invention is to provide a clearing centrifuge which does not have this disadvantage, i.e., in which the cutting angle of the clearing knife remains at least approximately constant throughout the entire operating range.

The clearing centrifuge according to the invention is characterised in that the holding part designed for the pivotable mounting of the knife carrier is mounted to be turnable about a pivot axis extending parallel to the axis of the centrifuge drum, that the pivot axis of the knife carrier extends eccentrically in relation to the pivot axis of the holding part, and that guide means connected to the centrifuge housing are provided, the said means so guiding the knife carrier that, during turning of the holding part, the cutting angle between the clearing knife and the layer to be cleared out remains at least approximately constant.

It is advantageous for the holding part to comprise a cylindrical-external surface, which serves for the sealing and rotatably mounting of the holding part in the centrifuge housing.

It is advantageous if the knife carrier is connected fast to a guide rod and the latter is guided by a guiding part pivotally connected to the centrifuge housing, the pivot axis of said guiding part extending parallel to the pivot axis of the holding part. If it is desired to produce an accurate parallel guiding of the knife carrier, it is expedient for the guide rod to be connected at its end remote from the holding part pivotally to the guiding part, for the distance between this point of connection and the pivot axis of the guiding part to be equal to that between the pivot axis of the knife carrier and the pivot axis of the holding part, and for the two spacing straight lines to extend parallel to one another, in such a way that, with a turning of the holding part, the knife carrier is moved parallel to itself.

It can also be expedient for the knife carrier to be guided by a pivotable guiding part which is directly connected to it inside the centrifuge housing and of which the pivot axis extends parallel to the pivot axis of the holding part. Again, if it is desired to produce an accurate parallel guiding of the knife carrier, it is expedient for the knife carrier to be pivotally connected to the guiding part at a position remote from the holding part, for the distance between this point of connection and the pivot axis of the guiding part to be the same as that between the pivot axis of the knife carrier and the pivot axis of the holding part, and for the two spacing straight lines to extend parallel to one another so that, with a turning of the holding part, the knife is moved parallel to itself.

BRIEF DESCRIPTION OF THE DRAWING The invention is hereinafter explained by way of example and by reference to the drawing, wherein:

FIG. 1 is a vertical axial section through a first embodiment of the invention, i.e., a clearing centrifuge;

FIG. 2 is an end view in the direction of the arrow A in FIG. 1, to show the clearing knife adjustment mechanism;

FIG. 3 is a section along the line IIIIII in FIG. 1, for showing the movement of the clearing knife;

FIG. 4 is an end view of a second constructional form of a clearing centrifuge, so as to show another clearing knife adjustment mechanism;

FIG. 5 is an end view of a third constructional form of a clearing centrifuge, for showing the clearing knife adjustment mechanism, and

FIG. 6 is a vertical axial section through another constructional form of a clearing centrifuge.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The centrifuge which is shown in FIG. 1, 2 and 3 comprises a housing 2 which includes a housing cover 1 and inside which a centrifuge drum 3 is arranged to be rotatable. Arranged inside the centrifuge drum 3 is a knife carrier 5 which is pivotable relatively to a holding part 4 and which comprises a clearing knife 6, which extends over the entire internal width of the centrifuge drum 3. The holding part 4, constructed for the pivotable mounting of the knife carrier 5, is mounted to be rotatable about a pivot axis 8 extending parallel to the centrifuge drum shaft 7. As can be seen from FIG. 2, a double-acting servomotor 9 eccentrically linked to the holding part 4 serves for the turning of the latter.

A pivot shaft 10 of the knife carrier 5 is arranged eccentrically by the radius r relatively to the pivot axis of the holding part 4, so that with a turning of the latter, the clearing knife 6 is moved in the drum 3 approximately radially in an outward or inward direction. Since the holding part 4 comprises a cylindrical external surface, it can in a simple manner be tightly and rotatably mounted in the housing, i.e., in its cover 1.

The knife carrier 5 is connected by way of its pivot shaft 10 fast to a guide rod llll which is disposed on the outside of the housing, the said guide rod being guided by a guiding part 12 pivotably mounted on the housing cover I. The pivot axis 13 of the guiding part 12 extends parallel to the pivot axis 8 of the holding part 4 and in a first plane a extending through the pivot axis of the holding part 4 and the cutting edge of the clearing knife 5. The connection point between the guide rod Ill and the guiding part 12 is arranged eccentrically by the radius r relatively to the pivot axis 13 of the guiding part 12.

This connection point and the pivot axis of the knife carrier 5 are thus disposed in a second plane b, which extends parallel to the first plane a, so that with a turning of the holding part 4, the second plate b is moved parallel to the first plane 0. Since a parallelogram guiding system is formed in this way, the knife carrier 5 is moved backwards and forwards, as shown in chain-dotted lines h andj in FIG. 3, the cutting angle of the clearing knife 6 remaining practically unchanged and the cutting edge consequently working over the entire operating range of the clearing knife 6 under best possible working conditions.

In FIG. 4 which shows an end view of a second constructional form of a clearing centrifuge provided with a clearing knife adjustment mechanism of a different construction, the guiding rod 11 serves simultaneously as a piston rod of a double-acting servomotor 14, this latter being fixed by means of laterally arranged guide pins 15 and 16 in the axial direction, but with a lateral displacement of the guiding rod 11, being likewise capable of displacement in a lateral direction.

In FIG. 5 showing an end view of another clearing centrifuge, the longitudinal axis of the guide rod 11 connected fast to the knife carrier 5 intersects the pivot axis of the guiding part 12. The pivot axis of the latter likewise extends parallel to the pivot axis of the holding part 4 and in a first plane 0 extending through the pivot axis of the holding part 4 and the cutting edge of the clearing knife 6. As a result of the guiding part 12' constructed and arranged in this way, the cutting edge of the clearing knife 6, as shown in chain-dotted lines, is displaced approximately in the plane a. The result is only a. quite small declination of the clearing knife 6, which is at its maximum in the middle pivotal range of the holding part 4, but is so small that the change in cutting angle occurring as a result thereof can be disregarded.

In FIG. 6 showing a longitudinal section through another constructional form of a clearing centrifuge, the only difference as compared with the constructional form shown in FIG. 1 is that the clearing knife is guided laterally by a guiding part 12" rotatably arranged inside the housing on the cover 1, so that the arrangement of a guide rod becomes superfluous. The principle of the parallelogram guiding system, as explained by reference to FIG. 1, 2 and 3, is however maintained.

If the pivot shaft 10 is constructed as a hollow shaft and the clearing knife 5 lies on a knife shaft mounted to be axially displaceable but non-rotatable relatively to said hollow shaft, the arrangements as described can also be used for a clearing knife which is displaceable axially in the drum 3; the servomotor for the displacement of the clearing knife can then be connected on one side to said knife shaft and on the other side to said hollow shaft or the holding part 4.

I claim:

1. A centrifuge comprising a housing, a drum rotatably mounted in said housing, and a clearing knife arranged in said drum for clearing from said drum a layer of centrifuged material; a knife carrier carrying said clearing knife; said knife carrier having a pivot shaft; a holding part for pivotably mounting said pivot shaft, said holding part being piviotably mounted in said housing, the axis of said pivot shaft and the pivot axis of said holding part being parallel to, and apart from each other; guide means connected to said housing and guiding said knife carrier, during turning of said holding part, so as to keep the cutting angle between said clearing knife and said layer at least approximately constant.

2. Centrifuge according to claim 1, in which said holding part has a cylindrical external surface, said surface serving as a journal for said pivotable mounting of said holding part in said housing and for sealing said holding part relatively to said housing.

3. Centrifuge according to claim 1 and a servomotor is connected to said holding part so as to turn said holding part about said pivot axis.

4. Centrifuge according to claim 1, in which said knife carrier comprises a guide rod, and said guide means comprises a guiding part; said guide rod being connected fast to said knife carrier; said guiding part being pivotally connected to said housing; the pivot axis of said guiding part and the pivot axis of said holding part being parallel to, and apart from each other.

5. Centrifuge according to claim 4, in which the radial distance of the pivot axis of said guiding part from the cutting edge of said clearing knife amounts at most to a third of the distance of said edge from the axis of said pivot shaft of the knife carrier; the longitudinal axis of said guide rod intersecting the pivot axis of said guiding part.

6. Centrifuge according to claim 4, in which said guide rod is, on its end remote from said holding part, connected pivotally to said guiding part; the distance between the connection point of said guide rod to said guiding part and the pivot axis of said guiding part being equal to the distance between the axis of said pivot shaft and the pivot axis of said holding part; the two straight lines corresponding to said distances being parallel to each other.

7. Centrifuge according to claim 1, and a servomotor connected to said knife carrier so as to displace said knife carrier relatively to said housing.

8. Centrifuge according to claim 1, in which said guiding part is arranged inside said housing. 

1. A centrifuge comprising a housing, a drum rotatably mounted in said housing, and a clearing knife arranged in said drum for clearing from said drum a layer of centrifuged material; a knife carrier carrying said clearing knife; said knife carrier having a pivot shaft; a holding part for pivotably mounting said pivot shaft, said holding part being pivotably mounted in said housing, the axis of said pivot shaft and the pivot axis of said holding part being parallel to, and apart from each other; guide means connected to said housing and guiding said knife carrier, during turning of said holding part, so as to keep the cutting angle between said clearing knife and said layer at least approximately constant.
 2. Centrifuge according to claim 1, in which said holding part has a cylindrical external surface, said surface serving as a journal for said pivotable mounting of said holding part in said housing and for sealing said holding part relatively to said housing.
 3. Centrifuge according to claim 1 and a servomotor is connected to said holding part so as to turn said holding part about said pivot axis.
 4. Centrifuge according to claim 1, in which said knife carrier comprises a guide rod, and said guide means comprises a guiding part; said guide rod being connected fast to said knife carrier; said guiding part being pivotally connected to said housing; the pivot axis of said guiding part and the pivot axis of said holding part being parallel to, and apart from each other.
 5. Centrifuge according to claim 4, in which the radial distance of the pivot axIs of said guiding part from the cutting edge of said clearing knife amounts at most to a third of the distance of said edge from the axis of said pivot shaft of the knife carrier; the longitudinal axis of said guide rod intersecting the pivot axis of said guiding part.
 6. Centrifuge according to claim 4, in which said guide rod is, on its end remote from said holding part, connected pivotally to said guiding part; the distance between the connection point of said guide rod to said guiding part and the pivot axis of said guiding part being equal to the distance between the axis of said pivot shaft and the pivot axis of said holding part; the two straight lines corresponding to said distances being parallel to each other.
 7. Centrifuge according to claim 1, and a servomotor connected to said knife carrier so as to displace said knife carrier relatively to said housing.
 8. Centrifuge according to claim 1, in which said guiding part is arranged inside said housing. 